They are some of the most iconic names and teams in sports history, and their greatness has become the standard by which all others are judged.

The Yankees of Joe DiMaggio and Mickey Mantle, who from 1949-64 won 14 pennants and from 1949-53 won five consecutive World Series.

The Bill Russell-Red Auerbach Celtics, who won 11 titles in 13 seasons in the Fifties and Sixties.

The Bulls of Michael Jordan and Phil Jackson, winners of six rings in the Nineties.

And now the Patriots have taken their rightful place among the all-time dynasties.

Win or lose against the Eagles on Sunday, the fact that the Patriots are in their eighth Super Bowl in Tom Brady’s 17 seasons as Bill Belichick’s quarterback is remarkable in and of itself. Should they win a sixth Super Bowl — which would make Brady unique and extend Belichick’s lead among coaches — it would add yet another magnificent accomplishment to a mind-boggling run.

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Where should the Patriots be put in historical perspective? At the very top of at least one important category.

Although they haven’t had the sustained success of the Yankees (27 world championships) or the Montreal Canadiens (24 Stanley Cups), you can draw a line of demarcation at free agency. Before it changed professional sports irrevocably, teams could keep players under contract indefinitely, so there were no concerns about having to break up championship teams.

But free agency drastically changed the competitive landscape, starting with Major League Baseball in 1976 and continuing with the NFL in 1993, the NHL in 1995 and the NBA in 1996. Keeping great teams together became virtually impossible, greatly diminishing the chances for sustained success.

New England Patriots starting quarterback Tom Brady, teammates and staff arrive on the team plane in a hangar at Minneapolis-St. Paul International Airport in Bloomington, Minnesota on Jan. 29, 2018. Photo Credit: LESSER/EPA-EFE/REX/Shutterstock / LESSER/EPA-EFE/REX/Shutterstock

That’s why the Brady-Belichick Patriots have been so remarkable in staying at or near the top since Brady replaced Drew Bledsoe early in the 2001 season. None of the league’s other championship teams could match their staying power. It is a testament to Brady’s greatness and longevity and to Belichick’s incredible ability to reconstruct teams from year to year despite significant roster turnover.

Of the Patriots’ 53 active players, 20 joined the team this season. Only six have been on the roster since 2011 or earlier. That’s an incredible rate of turnover, and no other team has been able to consistently boot and reboot from year to year the way Belichick has.

There are those who would argue that Belichick couldn’t have won five Super Bowls and be in position for a sixth without Brady, and that’s true. Brady is the greatest player in NFL history, and to put together a season like this one at age 40 — he’s expected to win the regular-season MVP award — is remarkable.

But Brady needs Belichick as much as the other way around. The coach’s incredible ability to dominate with game-day X’s and O’s and to shuffle lineups and win with dozens of different assistant coaches over the years is not only great but historically great. In all likelihood he will go down as the greatest coach in NFL history for what he has been able to do over such a prolonged period.

Vince Lombardi won five NFL championships, including two Super Bowls, from 1961-67. The 49ers’ Bill Walsh won three titles from 1981-88. Pittsburgh’s Chuck Noll won four from 1974-79. Great coaches and Hall of Famers one and all.

Like Belichick, they were fortunate to win all of their titles with a dominant quarterback. But it’s the span of success that gives Belichick the edge, and the era in which he has accomplished so much. Before free agency, it was easy to keep NFL teams together. Winning the Belichick way is unprecedented and might never happen again.

How do the Patriots measure up against these teams for sustained excellence?

Bob Glauber has been Newsday's national football columnist since 1992. He was Newsday's football writer covering the Jets and Giants, as well as the NFL, from 1989-91. He was selected as the New York State sportswriter of the year in 2015 and 2011 by the National Sports Media Association.